JP4896417B2 - Control device for internal combustion engine - Google Patents

Description

  The present invention relates to a control device for an internal combustion engine that switches a control mode of a variable valve lift device in accordance with the operating state of the internal combustion engine.

In recent years, an internal combustion engine mounted on a vehicle is equipped with a variable valve lift device that switches the lift amount of an intake valve or an exhaust valve, as described in Patent Document 1 (Japanese Patent No. 2827768), for example. There is. In Patent Document 1, the control mode of the variable valve lift device is switched between a first lift mode and a second lift mode according to the operating state of the internal combustion engine, and the intake valve is opened and closed in the first lift mode. The driving cam is switched to the first cam to reduce the lift amount of the intake valve, and in the second lift mode, the cam that drives the opening and closing of the intake valve is switched to the second cam to increase the lift amount of the intake valve. I am doing so.
Japanese Patent No. 2827768 (Pages 1 to 3 etc.)

  In general, when the control mode of the variable valve lift device is switched to change the valve lift amount, appropriate engine control parameters (for example, ignition timing, fuel injection amount, etc.) change accordingly. Further, there is a response delay from when the control mode switching command is output until the control mode of the variable valve lift device is actually switched.

  Therefore, as shown in FIG. 6, the present inventors set a predetermined delay time (time corresponding to the response delay time of the variable valve lift device) after the request control mode signal is switched and the control mode switching command is output. The estimated control mode signal is switched based on the assumption that the control mode of the variable valve lift device has been switched after the elapse of time, and a predetermined calculated retardation amount is calculated from the base ignition advance value corresponding to the control mode indicated by the estimated control mode signal. By subtracting the (retard amount corresponding to the required torque) to obtain the ignition advance value, the ignition timing is switched according to the switching of the estimated control mode signal, and the torque shock at the time of switching the control mode of the variable valve lift device We are researching a system to reduce the amount

  However, as shown in FIG. 6, depending on the specifications of the variable valve lift control system, the timing at which the control mode of the variable valve lift device is actually switched may be delayed with respect to the timing at which the estimated control mode signal is switched. In such a case, the period from when the estimated control mode signal is switched to when the control mode of the variable valve lift device is actually switched is before the control mode of the variable valve lift device is switched. Since the base ignition advance value corresponding to the control mode indicated by the later estimated control mode signal is adopted, as shown by the solid line in FIG. 7, the ignition timing is not appropriate when the control mode of the variable valve lift device is switched. Torque shock and knocking may occur and drivability may deteriorate.

  The present invention has been made in consideration of such circumstances, and therefore, the object of the present invention is to reduce torque shocks and the like when switching the control mode of the variable valve lift device, and at the time of switching the control mode. An object of the present invention is to provide an internal combustion engine control device capable of improving drivability.

In order to achieve the above object, the invention according to claim 1 switches the control mode signal of the variable valve lift device among a plurality of control modes having different lift characteristics by switching the required control mode signal according to the operating state of the internal combustion engine. In a control device for an internal combustion engine provided with a control mode switching means , when the control mode of the variable valve lift device is switched by the control mode switching means , the control mode of the variable valve lift device is switched immediately before the intake stroke of the specific cylinder. Control and switch the estimated control mode signal for estimating the control mode of the variable valve lift device when a predetermined time set according to the response delay time of the variable valve lift device elapses after the request control mode signal is switched configured, request control mode signal or the estimated control by the control parameter calculation means as The control parameters of the internal combustion engine are calculated based on the mode signal (hereinafter simply referred to as “control mode signal”), and the output valve of the crank angle sensor for detecting the crank angle is counted to actually calculate the variable valve lift device. During the period from when the control mode signal is switched by the control parameter correction means until the timing at which the control mode of the variable valve lift device is actually switched is detected (hereinafter referred to as this period). The control parameter calculated by the control parameter calculation means during the “control mode switching delay period” is continuously corrected based on the control parameter when the estimated control mode signal is switched.

In this configuration, the control parameter corresponding to the control mode indicated by the control mode signal after switching is calculated even though the control mode switching delay period is before the control mode of the variable valve lift device is switched. However, since the control parameter corresponding to the control mode after switching is corrected based on the control parameter when the estimated control mode signal is switched , the control mode before switching (actual control mode of the variable valve lift device) It is possible to correct near the control parameter corresponding to. As a result, torque shock and knocking at the time of switching the control mode of the variable valve lift device can be reduced to improve drivability.

  Specifically, as in claim 2, the control parameter calculated by the control parameter calculation unit immediately before the control mode signal is switched, and the control parameter calculated by the control parameter calculation unit immediately after the control mode signal is switched, May be obtained as a control parameter correction amount, and the control parameter calculated by the control parameter calculation means during the control mode switching delay period may be corrected using the control parameter correction amount.

  In this way, even if the control parameter corresponding to the control mode indicated by the control mode signal after switching is calculated during the control mode switching delay period, the control parameter corresponding to the control mode after the switching is calculated by the control parameter correction. Because it can be corrected using the amount (the difference between the control parameter corresponding to the control mode before switching and the control parameter corresponding to the control mode after switching), the control parameter corresponding to the control mode after switching is changed to the control mode before switching. It is possible to accurately correct the vicinity of the control parameter corresponding to (the actual control mode of the variable valve lift device).

  In general, the control parameters (for example, ignition timing, fuel injection amount, etc.) of the internal combustion engine are calculated so as to change according to the rotational speed and load of the internal combustion engine. The control parameter correction amount may be corrected based on at least one of the rotational speed and the load of the internal combustion engine during the period. In this way, since the control parameter calculated during the control mode switching delay period changes according to the rotational speed and load of the internal combustion engine, the control parameter correction amount can be corrected. The control parameters can be corrected with high accuracy regardless of the rotation speed and load.

Alternatively, as in claim 4, during the control mode switching delay period, the control parameter calculated by the control parameter calculation means is corrected using the control parameter correction amount, and the control parameter after correction and the control after a predetermined cycle are performed. You may make it repeat the process which updates a control parameter correction amount by the difference with the control parameter calculated by the parameter calculation means. In this way, the control parameter correction amount can be updated in response to changes in the control parameter calculated during the control mode switching delay period according to the rotational speed and load of the internal combustion engine. Control parameters can be corrected with high accuracy regardless of speed and load.

As in claim 5 , the control parameter to which the present invention is applied may be at least one of ignition timing, fuel injection timing, and fuel injection amount. In short, since the ignition timing, the fuel injection timing, and the fuel injection amount are control parameters that have a relatively large influence on the torque, the present invention is used to calculate these control parameters (ignition timing, fuel injection timing, fuel injection amount). If applied, torque shock at the time of control mode switching can be effectively reduced.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
First, a schematic configuration of the entire engine control system will be described with reference to FIG. An intake valve 13 is provided in each intake port 12 of each cylinder of the engine 11 that is an internal combustion engine, and an exhaust valve 15 is provided in each exhaust port 14 of each cylinder. The intake valve 13 is provided with a variable valve lift device 16 that changes the lift amount of the intake valve 13.

  The variable valve lift device 16 is configured to be able to switch the control mode between a low lift mode and a high lift mode in two stages. In the low lift mode, the cam for opening and closing the intake valve 13 is a low lift cam. By switching, the lift amount of the intake valve 13 is reduced, and in the high lift mode, the cam for opening and closing the intake valve 13 is switched to a high lift cam to increase the lift amount of the intake valve 13.

  A fuel injection valve 17 for injecting fuel is attached in the vicinity of the intake port 12 of each cylinder. A spark plug 18 is attached to the cylinder head of the engine 11 for each cylinder, and the air-fuel mixture in the cylinder is ignited by spark discharge of each spark plug 18.

  Further, the cylinder block of the engine 11 includes a coolant temperature sensor 19 that detects the coolant temperature, and a crank angle sensor 20 that outputs a pulse signal each time the crankshaft of the engine 11 rotates a predetermined crank angle (for example, 30 ° C.). It is attached. Based on the output signal of the crank angle sensor 20, the crank angle and the engine speed are detected.

  Outputs of these various sensors are input to an engine control circuit (hereinafter referred to as “ECU”) 21. A power supply voltage is supplied from a vehicle-mounted battery (not shown) to the power supply terminal of the ECU 21 via the main relay 22. The relay drive coil 22b that drives the relay contact 22a of the main relay 22 is connected to the main relay control terminal of the ECU 21, and the ON / OFF signal of the ignition switch 23 is input to the key SW terminal of the ECU 21. When the IG switch 23 is turned on, the main relay 22 is turned on and power supply to the ECU 21 and the like is started. When the IG switch 23 is turned off, the main relay 22 is turned off and power supply to the ECU 21 and the like is turned off. .

  The ECU 21 is mainly composed of a microcomputer, and executes various engine control programs stored in a built-in ROM (storage medium), so that the fuel injection amount and ignition of the fuel injection valve 17 according to the engine operating state. The ignition timing of the plug 18 is controlled. Further, the ECU 21 switches the request control mode signal according to the engine operating state, and switches the control mode of the variable valve lift device 16 between the low lift mode and the high lift mode according to the request control mode signal. At that time, the ECU 21 calculates the ignition timing as follows.

  As shown in FIG. 3, when the request control mode signal is switched and a control mode switching command is output, a process of counting up the count value of the estimation counter is started. Thereafter, when the count value of the estimated counter exceeds a predetermined value (a value corresponding to the response delay time of the variable valve lift device 16), it is determined that the control mode of the variable valve lift device 16 has been switched, and the estimated control mode Switch the signal and reset the count value of the estimation counter. The predetermined value (a value corresponding to the response delay time of the variable valve lift device 16) is set in advance for each engine operating state based on experimental data, design data, and the like.

As shown in FIG. 2, at the normal time (except for the control mode switching delay period described later), the base ignition advance angle corresponding to the control mode (low lift mode or high lift mode) indicated by the estimated control mode signal. When a retard angle request is calculated, the retard is made by a predetermined calculated retard amount (a retard amount corresponding to the requested torque) from the base ignition advance value corresponding to the control mode indicated by the estimated control mode signal. To determine the ignition advance value. This function serves as a control parameter calculation means in the claims.
Ignition advance value = Base ignition advance value-Calculated retard amount

  By the way, the variable valve lift control system of the present embodiment specifies that the cylinder in which the intake air amount first changes (hereinafter referred to as “intake change cylinder”) becomes a specific cylinder when the control mode of the variable valve lift device 16 is switched. Since the control mode of the variable valve lift device 16 is switched immediately before the intake stroke of the cylinder, the timing at which the control mode of the variable valve lift device 16 is actually switched with respect to the timing at which the estimated control mode signal is switched. There may be a delay. In such a case, the period from when the estimated control mode signal is switched to when the control mode of the variable valve lift device 16 is actually switched (hereinafter referred to as “control mode switching delay period”) is controlled by the variable valve lift device 16. Although it is before the mode is switched, the base ignition advance value corresponding to the control mode indicated by the estimated control mode signal after the switching is calculated.

Therefore, as shown in FIG. 2, when the estimated control mode signal is switched, the ECU 21 obtains a difference between the current base ignition advance value and the previous base ignition advance value. As a result, the base ignition advance value calculated immediately after the estimated control mode signal is switched (the base ignition advance value corresponding to the control mode indicated by the estimated control mode signal after the switch) and the estimated control mode signal are switched. The difference from the base ignition advance value calculated immediately before (the base ignition advance value corresponding to the control mode indicated by the estimated control mode signal before switching) is obtained, and this is used as the ignition advance value correction amount.
Ignition advance value correction amount = (current base ignition advance value)-(previous base ignition advance value)

After this, the timing at which the control mode of the variable valve lift device 16 is switched based on the count value (see FIG. 4) of the crank counter that counts the output pulses of the crank angle sensor 20 is passed (timing immediately before the intake stroke of the specific cylinder). By determining whether or not, it is determined whether or not the control mode switching delay period has ended. Then, before the end of the control mode switching delay period, that is, during the control mode switching delay period, a base ignition advance value corresponding to the control mode indicated by the estimated control mode signal after the switching is calculated, and this base ignition advance angle is calculated. The ignition advance value is obtained by subtracting the ignition advance value correction amount from the value.
Ignition advance value = Base ignition advance value-Ignition advance value correction amount

  Thereby, during the control mode switching delay period, the base ignition advance value corresponding to the control mode before switching (actual control mode of the variable valve lift device 16) corresponding to the control mode after switching is changed. The ignition advance value corrected in the vicinity is obtained. This function serves as a control parameter correction means in the claims.

  The ignition advance value calculated in this way is reflected in the ignition timing of the advance value reflecting cylinder determined based on the count value (see FIG. 4) of the crank counter that counts the output pulses of the crank angle sensor 20. When the control mode of the variable valve lift device 16 is switched, the ignition advance obtained by correcting the base ignition advance value corresponding to the control mode after the change with the ignition advance value correction amount until the advance angle reflecting cylinder becomes the intake change cylinder. When the angle value is used and the advance angle reflecting cylinder becomes the intake change cylinder, the ignition advance value retarded by the calculated delay amount from the base ignition advance value corresponding to the control mode after switching is used. .

The calculation of the ignition timing described above is executed by the ECU 21 according to the ignition timing calculation program shown in FIG. The processing contents of this program will be described below.
The ignition timing calculation program shown in FIG. 5 is executed at a predetermined cycle while the ECU 21 is powered on. When this program is activated, it is first determined in step 101 whether or not the estimated control mode signal has been switched. When it is determined in step 101 that the estimated control mode signal has been switched, the process proceeds to step 102 where the estimated control mode is determined by obtaining the difference between the current base ignition advance value and the previous base ignition advance value. Base ignition advance value calculated immediately after the signal is switched (base ignition advance value corresponding to the control mode indicated by the estimated control mode signal after switching) and base ignition calculated immediately before the estimated control mode signal is switched The difference from the advance value (the base ignition advance value corresponding to the control mode indicated by the estimated control mode signal before switching) is obtained and used as the ignition advance value correction amount.

Ignition advance value correction amount = (current base ignition advance value)-(previous base ignition advance value)
After the estimated control mode signal is switched, the process proceeds from step 101 to step 103, and the timing at which the control mode of the variable valve lift device 16 is switched based on the count value of the crank counter (see FIG. 4) (intake of a specific cylinder) It is determined whether or not the control mode switching delay period has ended by determining whether or not the timing immediately before the stroke has passed.

When it is determined in step 103 that the control mode switching delay period is before the end, that is, during the control mode switching delay period, the routine proceeds to step 104 where the ignition advance value correction amount is set to the previous ignition advance value. Hold the correction amount.
Ignition advance value correction amount = Previous ignition advance value correction amount

Thereafter, the process proceeds to step 105, and the retard amount reflection flag is reset or maintained at “0” which means that the calculated retard amount is not reflected in the ignition advance value. As a result, it is determined as “No” in the next step 108, and the process proceeds to step 109, in which the ignition advance value correction amount is subtracted from the base ignition advance value corresponding to the control mode indicated by the estimated control mode signal after switching. To obtain the ignition advance value.
Ignition advance value = Base ignition advance value-Ignition advance value correction amount

  Thereby, during the control mode switching delay period, the base ignition advance value corresponding to the control mode before switching (actual control mode of the variable valve lift device 16) corresponding to the control mode after switching is changed. The ignition advance value corrected in the vicinity is obtained.

Thereafter, if it is determined in step 103 that the control mode switching delay period has ended, the routine proceeds to step 106 where the ignition advance value correction amount is reset or maintained to zero.
Ignition advance value correction amount = 0

Thereafter, the process proceeds to step 107, and the retardation amount reflection flag is set or held at the same value as the retardation request flag corresponding to the retardation request. If there is a retardation request (retard amount reflection flag = retardation request flag = 1), “Yes” is determined in the next step 108, the process proceeds to step 110, and the control indicated by the estimated control mode signal is performed. From the base ignition advance value corresponding to the mode, the ignition advance value is obtained by retarding by the calculated retard amount (retard amount corresponding to the required torque).
Ignition advance value = Base ignition advance value-Calculated retard amount

  In the present embodiment described above, when the estimated control mode signal is switched, the difference between the base ignition advance values before and after the switching is obtained as the ignition advance value correction amount, and the control mode switching delay period (estimated control mode signal During the period from when the engine is switched to when the control mode of the variable valve lift device 16 is actually switched), the base ignition advance value corresponding to the control mode indicated by the estimated control mode signal after switching is calculated. The base ignition advance value corresponding to the later control mode is corrected by the ignition advance value correction amount to obtain the ignition advance value, so the base ignition advance value corresponding to the control mode after switching is changed before switching. The ignition advance value corrected in the vicinity of the base ignition advance value corresponding to the control mode (actual control mode of the variable valve lift device 16) can be obtained. Thereby, as shown by a broken line in FIG. 7, torque shock and knocking at the time of switching the control mode of the variable valve lift device 15 can be reduced to improve drivability.

  In the above embodiment, during the control mode switching delay period, the ignition advance value correction amount is maintained at the previous ignition advance value correction amount. However, in general, the base ignition advance value is determined by the engine speed. Therefore, the ignition advance value correction amount may be corrected in accordance with the engine speed and load during the control mode switching delay period. In this way, the ignition advance value correction amount can be corrected in response to the base ignition advance value calculated during the control mode switching delay period changing according to the engine speed and load. The base ignition advance value can be accurately corrected regardless of the engine speed and load.

Alternatively, in the control mode switching delay period, the calculated base ignition advance value is corrected using the ignition advance value correction amount, and the corrected base ignition advance value and the base ignition advance calculated after a predetermined period are used. You may make it repeat the process which updates ignition advance value correction amount by the difference with an angle value. In this way, the ignition advance value correction amount can be updated in response to changes in the base ignition advance value calculated during the control mode switching delay period according to the engine speed and load. The base ignition advance value can be accurately corrected regardless of the rotation speed and load.

  Further, the base ignition advance value corresponding to the estimated control mode signal before switching may be calculated during the control mode switching delay period. In this way, the base ignition advance value corresponding to the control mode before switching (actual control mode of the variable valve lift device 16) before the control mode switching delay period can be calculated. It is possible to improve drivability by reducing torque shock and knocking during control mode switching.

  In the above embodiment, the present invention is applied to the calculation of the ignition timing. However, the present invention is not limited to the ignition timing, and the present invention is used to calculate engine control parameters such as the fuel injection timing, the fuel injection amount, the throttle opening, and the valve timing. May be applied.

  In the above embodiment, the present invention is applied to a system that calculates an engine control parameter according to an estimated control mode signal. However, the present invention is applied to a system that calculates an engine control parameter base according to a required control mode signal. May be.

  In the above embodiment, the present invention is applied to a system that switches the control mode of the variable valve lift device on the intake side. However, the present invention may be applied to a system that switches the control mode of the variable valve lift device on the exhaust side. .

  In the above embodiment, the present invention is applied to a system equipped with a variable valve lift device that switches between two control modes (between the low lift mode and the high lift mode). You may apply this invention to the system which mounts the variable valve lift apparatus switched between.

It is a schematic block diagram of the whole engine control system in one Example of this invention. It is a time chart explaining the calculation method of the ignition timing of a present Example. It is a time chart explaining an estimation control mode signal. It is a time chart which shows the behavior of a crank counter. It is a flowchart which shows the flow of a process of an ignition timing calculation program. It is a time chart explaining the calculation method of the ignition timing of a comparative example. It is a time chart explaining the effect of a present Example.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 11 ... Engine (internal combustion engine), 13 ... Intake valve, 15 ... Exhaust valve, 16 ... Variable valve lift device, 17 ... Fuel injection valve, 18 ... Spark plug, 20 ... Crank angle sensor, 21 ... ECU (control parameter calculation means) , Control parameter correction means)

Claims (5)

A variable valve lift device that switches the lift characteristics of an intake valve or an exhaust valve of an internal combustion engine, and a control mode signal of the variable valve lift device that switches the request control mode signal according to the operating state of the internal combustion engine, and a plurality of different lift characteristics. In a control device for an internal combustion engine comprising control mode switching means for switching between control modes,
The control mode switching means controls to switch the control mode of the variable valve lift device immediately before the intake stroke of the specific cylinder when the control mode of the variable valve lift device is switched,
Means for switching an estimated control mode signal for estimating a control mode of the variable valve lift device when a predetermined time set according to a response delay time of the variable valve lift device has elapsed since the request control mode signal was switched. When,
A control parameter calculating means for calculating a control parameter of the internal combustion engine in response to the request control mode signal or the estimated control mode signal (hereinafter referred to simply "control mode signal"),
Means for detecting the timing at which the control mode of the variable valve lift device is actually switched by counting the output pulses of the crank angle sensor for detecting the crank angle;
Calculation of the control parameter during a period from when the control mode signal is switched to when the timing at which the control mode of the variable valve lift device is actually switched is detected (hereinafter, this period is referred to as a “control mode switching delay period”). And a control parameter correction unit that continuously corrects the control parameter calculated by the control unit based on the control parameter when the estimated control mode signal is switched.   The control parameter correction means includes a control parameter calculated by the control parameter calculation means immediately before the control mode signal is switched, and a control parameter calculated by the control parameter calculation means immediately after the control mode signal is switched. 2. The internal combustion engine according to claim 1, wherein the difference is obtained as a control parameter correction amount, and the control parameter calculated by the control parameter calculation means is corrected using the control parameter correction amount during the control mode switching delay period. Control device.   3. The internal combustion engine according to claim 2, wherein the control parameter correction unit corrects the control parameter correction amount based on at least one of a rotational speed and a load of the internal combustion engine during the control mode switching delay period. Control device.   The control parameter correction means includes a control parameter calculated by the control parameter calculation means immediately before the control mode signal is switched, and a control parameter calculated by the control parameter calculation means immediately after the control mode signal is switched. A difference is obtained as a control parameter correction amount, and during the control mode switching delay period, the control parameter calculated by the control parameter calculation means is corrected using the control parameter correction amount, and the control parameter after correction and a predetermined period 2. The control apparatus for an internal combustion engine according to claim 1, wherein a process of updating the control parameter correction amount with a difference from the control parameter calculated by the control parameter calculating means is repeated.   5. The control apparatus for an internal combustion engine according to claim 1, wherein the control parameter is at least one of an ignition timing, a fuel injection timing, and a fuel injection amount.

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